An observational study published in Nutrition Journal examined for the first time if tea and coffee consumption is associated with blood levels of vitamin D.
330 Saudi adolescents were randomly selected from an existing cohort to participate in the cross-sectional study. The adolescents filled out questionnaires on how much coffee and tea they consumed, and subjects were divided into groups based on how many cups of tea and coffee they drank per week.
Subjects were also questioned on their level of physical activity and how often they received sun exposure. Height and weight were recorded and blood samples were collected for analysis after an overnight fast.
In both males and females, there was a statistically significant association between age BMI, and coffee consumption, with the youngest and leanest subjects reporting the greatest consumption of coffee. In males, those with the highest consumption of coffee had the highest levels of HDL and LDL cholesterol. This same trend was noted in females, but only the association between HDL cholesterol and coffee consumption was significant.
Interestingly, 25(OH)D levels were highest in females with the greatest level of coffee consumption, but in males there was no statistically significant relationship between coffee consumption and circulating vitamin D. For tea consumption, in both sexes, those who consumed more cups of tea per week had higher levels of vitamin D.
It is worth noting that even Saudi adolescents in the highest category of vitamin D levels still only averaged a level of 24.2 nmol/l (9.7 ng/mL), a shocking deficiency state even by conservative standards. Adolescents in the lowest 25(OH)D serum category averaged blood levels of 19.8 nmol/l (7.9 ng/mL).
Lack of data on outdoor physical activity and diet were major confounders to the study, and the type of coffee and tea were not taken into consideration. Nevertheless, the data suggests that an oh-so slight elevation of vitamin D levels may be another interesting benefit to your favorite hot caffeinated beverage, though this doesn’t appear to be a profound effect by any means.